Olive collection systems have a profound effect on the quality of the resulting oil.
In the areas of production of oils with a very low acid content (the most valuable), the collection is done by hand, directly from the plant. But this is only done in family farms and of modest dimensions: groves of up to 50 plants.
If the collection is delayed, the natural fall of the fruit appears: the olive. Once the fruit in the soil undergoes a series of alterations that deteriorate the quality of the oils obtained. Essentially the acidity increases as the time that remains on the ground passes.
Free oleic acid
The acidity of olive oil can only be defined by laboratory chemical analysis.
Free oleic acid in the oil can increase if an enzyme called lipase acts. The process can be intensified especially:
- If the olive has suffered a cellular injury: insect attack, injury during collection and transport, poor agricultural and environmental status
- The enzymatic activity of lipase is also favored by fairly high temperatures, between 30 ° C and 40 ° C.
It is classified as extra virgin olive oil that oil with a free acid content of less than 0.8 g / liter.
Acidity of olive oil
The degree of acidity of an olive oil is strongly influenced by:
- the health status of olives,
- the technique of harvesting,
- the storage time,
- the processing technology adopted (eg high kneading temperatures)
- and the care taken by the operators in the treatment and storage of the product.
Olive oils classification
Based on the quality of the olives, their freshness and integrity, degree of acidity and type of processing, olive oils are classified as follows:
1. EXTRA VIRGIN OLIVE OIL:
"Olive oil of superior category obtained directly from olives and only by mechanical procedures". Not exceeding 0,8 °, expressed as a percentage of free oleic acid.
2. VIRGIN OLIVE OIL:
"Olive oil obtained directly from olives and only by mechanical means". Can not exceed 2 ° acidity. The median of defects must be less than 3.5 and the median of fruity greater than 0
3. OLIVE OIL: Contains exclusively refined olive oils and virgin olive oils:
It is the result of the mixture between;
- a grinding oil, which has undergone a chemical process which is aimed at the elimination of chemical and organoleptic defects
- and a virgin olive oil.
The legislation does not establish a minimum amount of virgin olive oil that should go into the mix. It is usually a minimal percentage, enough to restore the color, smell and taste to the oil. Which translates to a rather 'flat' complex.